Comparison system, comparison method and computer readable medium

Abstract

A comparison system includes a key generation means for generating a common key being common to each of a plurality of pieces of registration information, and also generating a plurality of unique keys being unique for each of the plurality of pieces of registration information by using a plurality of pieces of identification information, a concealment means ( 126 ) for generating a plurality of pieces of concealment information. The client includes a concealment index calculation means for calculating a plurality of concealment indexes representing a similarity degree between comparison information and each of the plurality of pieces of concealment information. The verification server includes a determination means for generating a plurality of indexes acquired by decrypting each of the plurality of concealment indexes, and also performing authentication of the comparison information, based on whether any of the plurality of indexes indicates a value within a predetermined range.

What is claimed is: 
     
         1 . A comparison system comprising:
 at least one first memory storing program instructions; and   at least one first processor coupled to the at least one first memory, the at least one first processor being configured to execute the program instructions stored in the at least one first memory to:
 generate a common random number; 
 generate a plurality of pieces of identification information being unique for each of a plurality of pieces of registration information being a plurality of pieces of biometric information about a plurality of registrants; 
 generate a common key being common to each of the plurality of pieces of registration information by using the common random number, and also generate a plurality of unique keys being unique for each of the plurality of pieces of registration information by using the plurality of pieces of identification information; and 
 generate a plurality of pieces of concealment information in which each of the plurality of pieces of registration information is concealed by using the common key and the plurality of unique keys, 
   the comparison system further comprising:   a client; and   a verification server, wherein   the client comprises:
 at least one second memory storing program instructions; and 
 at least one second processor coupled to the at least one second memory, the at least one second processor being configured to execute the program instructions stored in the at least one second memory to: 
 calculate a plurality of concealment indexes representing a similarity degree between comparison information being biometric information about an authenticated subject, and each of the plurality of pieces of concealment information, and 
   the verification server comprises:   at least one third memory storing program instructions; and   at least one third processor coupled to the at least one third memory, the at least one second processor being configured to execute the program instructions stored in the at least one third memory to
 generate a plurality of indexes acquired by decrypting each of the plurality of concealment indexes by using the common key and the plurality of unique keys, and also perform authentication of the comparison information, based on whether any of the plurality of indexes indicates a value within a predetermined range. 
   
     
     
         2 . The comparison system according to  claim 1 , wherein in the authentication of the comparison information, the authentication is accepted when any one of the plurality of indexes indicates a value within the predetermined range. 
     
     
         3 . The comparison system according to  claim 1 , wherein
 each of the unique keys is formed of a secret key and a public key, and   in the generation of the key, a secret key of each of the unique keys is used to generate the concealment information, and a public key of each of the unique keys is transmitted to the verification server.   
     
     
         4 . The comparison system according to  claim 1 , wherein
 in the verification server, the at least one third processor is further configured to execute the program instructions stored in the at least one third memory to   generate a challenge signal for each piece of the comparison information, and transmit the challenge signal to the client, and   in the client, in the calculation of the concealment index, the plurality of concealment indexes are calculated as a response signal being associated with the challenge signal.   
     
     
         5 . The comparison system according to  claim 1 , wherein the comparison information and the plurality of pieces of registration information are both represented by a vector. 
     
     
         6 . The comparison system according to  claim 1 , wherein in the client, in the calculation of the concealment index, the plurality of concealment indexes are calculated by an inner product of the comparison information and each of the plurality of pieces of concealment information. 
     
     
         7 . The comparison system according to  claim 1 , wherein at least the generation of the identification information, the generation of the key, and the generation of the concealment information are performed in the client. 
     
     
         8 . The comparison system according to  claim 1 , wherein at least the generation of the identification information, the generation of the key, and the generation of the concealment information are performed in a registration server different from the client and the verification server. 
     
     
         9 . A comparison method comprising:
 generating a common random number;   generating a plurality of pieces of identification information being unique for each of a plurality of pieces of registration information being a plurality of pieces of biometric information about a plurality of registrants;   generating a common key being common to each of the plurality of pieces of registration information by using the common random number, and also generating a plurality of unique keys being unique for each of the plurality of pieces of registration information by using the plurality of pieces of identification information;   generating a plurality of pieces of concealment information in which each of the plurality of pieces of registration information is concealed by using the common key and the plurality of unique keys;   in a client, calculating a plurality of concealment indexes representing a similarity degree between comparison information being biometric information about an authenticated subject, and each of the plurality of pieces of concealment information; and   in a verification server, generating a plurality of indexes acquired by decrypting each of the plurality of concealment indexes by using the common key and the plurality of unique keys, and also performing authentication of the comparison information, based on whether any of the plurality of indexes indicates a value within a predetermined range.   
     
     
         10 . A non-transitory computer readable medium storing a comparison program causing a computer to execute:
 common random number generation processing of generating a common random number;   identification information generation processing of generating a plurality of pieces of identification information being unique for each of a plurality of pieces of registration information being a plurality of pieces of biometric information about a plurality of registrants;   key generation processing of generating a common key being common to each of the plurality of pieces of registration information by using the common random number, and also generating a plurality of unique keys being unique for each of the plurality of pieces of registration information by using the plurality of pieces of identification information;   concealment processing of generating a plurality of pieces of concealment information in which each of the plurality of pieces of registration information is concealed by using the common key and the plurality of unique keys;   in a client, concealment index calculation processing of calculating a plurality of concealment indexes representing a similarity degree between comparison information being biometric information about an authenticated subject, and each of the plurality of pieces of concealment information; and   in a verification server, determination processing of generating a plurality of indexes acquired by decrypting each of the plurality of concealment indexes by using the common key and the plurality of unique keys, and also performing authentication of the comparison information, based on whether any of the plurality of indexes indicates a value within a predetermined range.